This invention relates to belt guide pulleys. More particularly it relates to belt guide pulleys which may be used with large diameter shafts having a low moment of inertia and a high bending modulus.
Conveyor machines for moving textile articles such as towels and the like often include a plurality of parallel endless belts which operate between spaced apart shafts. Each shaft normally includes a plurality of pulleys which are attached to the respective shafts. The belts ride on the pulleys which maintain the belts in proper alignment. Normally the shafts are made of 1" diameter steel. Because between 50 and 60 pounds or more of force is applied by each belt to the shaft, there are limitations to the length of the shaft and thus the width of the conveyor.
A typical prior art small diameter shaft and pulley system is shown in FIG. 1. Pulley 10 is attached to 1" shaft 12. Pulley 10 includes support web 14 having keyed hole 16 for receiving the shaft. Shaft 12 also includes key 18 which is received in slot 20 of web 14. The key 18 must be machined when the shaft is manufactured thereby increasing the cost. Pulley 10 includes outside surface 22 for making contact with a conveyor belt. Surface 22 may be crowned to keep the conveyor belt in proper alignment.
Typical pulleys having support webs on the inside thereof are shown in U.S. Pat. Nos. 605,104 issued to Knoblock and 1,959,972 issued to Wanamaker. U.S. Pat. Nos. 4,439,173 issued to Fokos, 3,010,332 issued to Skates, and 4,718,544 issued to Herren show pulleys having an internal web structure as set forth above, and also having an additional outer covering for the outside surface of the pulley which, in the case of the Fokos and Skates patents, are initially in two halves.
For wider conveyors larger diameter shafts are used. In some cases the pulleys are machined onto the shaft during the construction of the shaft. In other cases, because of the machining expense, pulleys are omitted and guides adjacent to the shaft are used to keep the belts aligned. These guides cause excessive wear on the belts.